Safety-lock door chain



Jan. 6, 1959 E. P. BUGGE 2,867,453

SAFETY-LOCK DOOR CHAIN I Filed July 18, 1955 8 11 10 I i ii 1 25 i 1 1! I I K 1"... I v i I 15 W 17 IN VEN TOR. iezwa 2 Bua'aE SAFETY-LOCK DOOR CHAIN Erling P. Bugge, Los Angeles, Calif. Application July 18, 1955, Serial No. 522,576

7 Claims. (Cl. 292-264) This invention relates to door chains, and more particularly, to a door chain which is locked in connected position by a safety spring which prevents uncoupling the chain unless the safety spring is disengaged.

The well-known door chain locking device consists of a chain plate, usually mounted on the frame at one side of the doors swinging edge, a locking plate on the door,

and a chain from the chain plate terminating in a coupler has been able to slip a thin piece of metal through the Y restricted space at the edge of the partially opened door and, by lifting the chain, has been able to cause the coupler to rise to the top of the slot and fall out of it.

It is a primary object of the present invention to provide a door chain which cannot be thus uncoupled from the outside. A related object is to provide a door chain which cannot be readily unlocked by small children.

It is a further object to provide a door chain which need not have the locking plate vertically mounted, but may be installed with the locking plate horizontal or oblique without increasing the risk of unwanted unlocking.

Still another object is to provide a door chain which is capable of simple and economic construction of stamped parts.

The foregoing objects are accomplished by providing the locking plate with a spring safety catch analogous to that used on certain guns, for example, the catch being comprised of a locking spring and, preferably, a button for disengaging said spring. In its preferred form, the invention employs a coupler of novel design, which, instead of being formed as a rather bulky button, or coupling plug, is formed out of sheet metal and adapted to enter the slotted socket of the locking plate by way of an opening not much greater, in one dimension, than the thickness of the sheet metal from which the coupler is formed.

A specific embodiment of this invention will be disclosed by description of the accompanying drawings, in which:

Figure 1 is a perspective view of the chain lock as mounted on door and frame, and coupled in locked position;

Figure 2 is a vertical sectional view taken through the locking plate of Figure l as seen in the direction indicated by the arrows 2-2;

Figures 3 and 4 are sectional views similar to that of Figure 2 but showing the door chain at two stages of uncoupling; and

- chain plate 11 is correspondingly shown in a vertical position as it would be mounted on the adjoining frame of a door. The line of closure between the swinging edge of the door and the edge of the frame is suggested by the two dashed lines 12. Ordinarily, locking plate 10 and chain plate 11 are mounted by means of wood screws inserted through locking plate screw holes 13 and chain plate screw holes 14. A locking chain 15 is permanently attached to chain plate 11 by means of a staple 16 and may be attached at the other end to locking plate 10 by means of a coupler 17, which is connected to the end of the chain 15 by means of a staple 18. Chain plate 11 is provided with a slot 19 for holding coupler 17, when.

the door chain is not in use.

Among the important novel features of this chain lock are the locking spring Zil, seen in dashed outline in Figure 1, and the coupler 17, which is' shaped in a unique manner to cooperate in: locking engagement with spring 2i) and to be difficult of removal by manipulation of chain 15 from outside the door.

As seen in Figure 2, locking plate if is stamped from sheet metal or otherwise formed to provide a flanged edge 22 around its periphery. When lo-ckingplate 10 is mounted on a door, there is a'clearance, usually a fraction of an inch, between its inner surface and the surface of the door. Spring 20 is mounted within this space by attachment to the under surface of locking plate 10, preferably by spot weldingas indicated at 23. The deflecting end 24 of spring 20 (the lower end as viewed in the drawings) is seen to have a normal undeflected position fiat against the inner surface of locking plate 10, the deflecting end 24 terminating at such a point, that coupler 17 may be received in the lower end of a slot 25 with spring 20 in an undeflected position. Coupler 17 cannot be removed with spring 20 in the position shown in Figure 2. It is necessary that spring 20 be inwardly deflected as shown in Figures 3 and 4 to permit the upward withdrawal of coupler 17, as indicated by the arrow 26.

Spring 2% is depressed by means of a button 37 near its upper or anchored end, which button protrudes from the face of locking plate 10 through a hole 28 provided for this purpose.

In order to permit ready insertion and removabof coupler 17 through the transverse slot insertion opening 25a, spring 20 is formed with an inward offset 29 opposite the insertion opening 25a to permit movement of coupler 17 through the opening and along slot 25 near the anchored end 23 of spring 20.

' In Figure 5 coupler 17 is seen to be shaped in the form of a narrow section of channel, each flange of which is notched on each side by notches 39 to provide a pair of T-shaped plates 31 and 32, which engage that portion of the plate 10 forming the edges of slot 25. It will be evident from the position of coupler 17 during movement through insertion opening 25a as seen in Figure 4, that channel-shaped coupler 17 preferably presents an aspect sufficiently recessed on its underside to permit ready removal over button 27. The preferred coupling illustrated cannot be removed by tugging at the chain, even when leaf spring 26 is deflected, because there are two parts which engage the walls of the slot 25, and each must be separately slipped through the very restricted slot opening 250:.

Patented Jan. 6, 1959 It will be understood, of course, that chain 15 could be replaced by a cable or strap or other equivalent means;

however, the term chain will be used here as inclusive of all such equivalents.

-While the foregoing specification describes in detail one specific embodiment of the invention, it is not the intention of the inventor to 'be restricted to the form shown, but to include all forms falling within the scope of; the appended claims.

lclai-m: I p p p 1. A door chain device whichincludes: a chain plate; a chain permanently attached 'at one end to said chain plate; a coupler attached to theopposite .end of said chain and having means to engage the walls of a slot for holding said coupler; a locking plate provided with a slot for receiving said coupler, the walls of said slot engaging and holding said coupler, said slot being enlarged at one end to provide an insertion opening for said c upler; and a leaf spring extending along said slot, said leaf spring being anchored to said locking plate at a point beyond said insertion opening end of said slot, and said spring terminating at its opposite unanchored end part way along said slot in a position to engage and block the movement of said coupler in said slot beyond the end of said leaf spring, whereby. said coupler is normally held by said spring from moving within said slot toward said insertion opening from the opposite end of said slot.

2. A door chain device which includes: a mountable chain plate; a chain permanently attached at one end to said .plate; a coupler attached to the opposite end of said chain and having means to engage the walls ofa slot'for holding said coupler; an elongated locking plate provided with a longitudinally extended slot having an insertion opening at one end, said insertion opening being adapted to receive said coupler and the walls of said slot being adapted to hold said coupler in engagement throughout the length of said slot, including a locking position for said coupler at the end of said slot opposite said insertion opening; a leaf spring disposed along said slot in the portion adjacent said insertion opening and anchored to the underside of said locking plate at a point beyond the insertion opening end of said slot, the unanchored end of said spring being adapted and positioned to engage said coupler and block its movement in said slot toward said insertion opening; and a button on said leaf spring accessible through an opening in said locking plate.

3. A- door chain device as described in claim2 in which said button is located between said anchored end of said leaf spring and said insertion opening, and said button protrudes from the outer surface of said locking plate.

4. A door chain device as described in claim 2 in which said leaf spring is. formed with an inwardlydisplaced section in the region of said insertion opening to facilitate movement of said coupler through said insertion opening.

5. A door chain device which includes: a mountable chain plate; a chain permanently attached at one end to said plate; a coupler attached to the opposite end of said chain and having means to engage the walls of a slot for holding said coupler; an elongated locking plate provided with a longitudinally extended slot having an insertion opening at one end and adapted toreceive saidcoupler through said insertion opening and to hold said coupler in engagement throughoutthelength of said slot including. a. locking pos t fo a ou le a tire end of said slot opposite said insertion opening; a leaf spring disposed along said slot-in the portion adjacent said insertion opening and anchored to the underside of said locking plate at a point beyond the insertion opening end of said slot, the opposite end of said spring being positioned and arranged to engage said coupler and block its movement fromisaid locking position; a button comprisedof a portion of said/spring material displaced out-' wardly to provide a button-like protrusion, and said locking plate having an opening. forsuch protrusion to project from the outer face of said locking plate when said leaf spring is in an undeflected position.

6. A door chain device which includes: a chain plate, achain having one end permanentlyattached to said chain plate; a coupler attached to.the opposite end of said chain and having means to engage the walls ofra slot for holding :said coupler; .a locking plate having a Slot therein,-said slot being enlarged at one end to receive said couplen-the portion of theplate bordering the remainder ;of said slot being adapted to engage and retain said coupler; and spring meanshaving. one end anchored to said locking plate adjacent .said enlarged portion .ofsaid slot, said spring-meansextending along said slot and terminating short of the other end thereof, the free end of said spring means being engageable with said coupler to prevent the movement thereof within said slot toward said enlarged portion from the opposite end.

7. A door chain device as described in claim 6 in which said spring means is provided with button means adjacent its anchored end,.-whereby the opposite end of said spring means is manually movable away from said slot to disengage said coupler, thereby permitting the movement of said coupler to said enlarged portion of said slot.

References Cited in the file of this patent UNITED STATES PATENTS 

